Extract/extractValue for tags with a namespace

Question

I am trying to extract the value of a tag with a name space in Oracle 10g. My query is

select      extract(xmltype(xml_text),
            '/feed/entry[1]/yt:statistics',
            'xmlns:yt="http://gdata.youtube.com/schemas/2007"') title
from    edgecast_xml
where   load_date > sysdate-1

and it returns null

The original xml is this (I had to label as htp as opposed to http to avoid links):

<feed xmlns='htp://www.w3.org/2005/Atom' xmlns:media='htp://search.yahoo.com/mrss/' xmlns:openSearch='htp://a9.com/-/spec/opensearch/1.1/' xmlns:gd='htp://schemas.google.com/g/2005' xmlns:yt='http://gdata.youtube.com/schemas/2007' gd:etag='W/&quot;D0YEQH88eSp7I2A9XRZQEU8.&quot;'>
    <entry gd:etag='W/&quot;CUMNRH47eCp7I2A9XRZRGUo.&quot;'>
       <id>tag:youtube.com,2008:video:qXPtXPJLnJY</id>
       <updated>2014-06-17T02:51:35.000Z</updated>
       <category scheme='http://schemas.google.com/g/2005#kind' term='http://gdata.youtube.com/schemas/2007#video'/>
       <category scheme='http://gdata.youtube.com/schemas/2007/categories.cat' term='Nonprofit' label='Nonprofits &amp; Activism'/>
       <title>Rear Admiral Lee Addresses Restrictive Regulations on Religious Liberty</title>
       <gd:rating average='4.8343196' max='5' min='1' numRaters='5239' rel='http://schemas.google.com/g/2005#overall'/>
       <yt:statistics favoriteCount='0' viewCount='365565'/>
       <yt:rating numDislikes='217' numLikes='5022'/>
   </entry>
</feed>

Why am I getting null? If I select just /feed/entry[1] it returns xml for everything within the entry tag.

Answer 1

Since you are getting a result when you use /feed/entry[1] it seems that your default (Atom) namespace is automatically registered. The yt namespace is registered as well, so it should work.

You get null when you extract the string value of /feed/entry[1]/yt:statistics because the <yt:statistics> element has no text content. It's an empty tag. But you can read its attributes:

/feed/entry[1]/yt:statistics/@viewCount

and

/feed/entry[1]/yt:statistics/@favoriteCount